Unveiling the Mystery: How Do Noise-Canceling Headphones Work?

December 15, 2023

With the growing popularity of noise-canceling headphones, many people are curious about how they actually work. Today, 1MORE is here to unravel the secrets behind these incredible devices.

There are two types of noise cancellation: active and passive. Passive noise cancellation relies on the physical structure of the headphones to block out sound, making it a more affordable option. However, we'll be focusing on active noise cancellation, which offers superior performance.

Active noise cancellation doesn't eliminate noise; instead, it generates a special noise that neutralizes external sounds. When sound waves with the same phase meet, they amplify each other, creating a louder sound. Conversely, when sound waves with opposite phases (180° out of phase) meet, they cancel each other out, resulting in reduced sound. If the frequency of the opposite-phase waves perfectly matches the original sound, it disappears completely. This is the principle behind noise-canceling headphones.

You might be wondering, do noise-canceling headphones emit reverse sound waves? Rest assured, sound waves are mechanical waves, and when two signals with the same waveform but opposite phases overlap, they interfere with each other, effectively canceling out both waves. Think of it like Tetris, where a concave-shaped noise is countered with a convex-shaped noise, ultimately eliminating the unwanted sound. In the past, this technology was primarily used in aviation and military applications due to its high cost. However, thanks to advancements in electronics, it has become more accessible in civilian headphones in recent years.

Active noise cancellation in headphones typically falls into three categories:

Feed-forward noise cancellation:

This type of noise cancellation involves an external microphone that collects ambient noise.
The collected noise is sent to a digital signal processor (DSP) for noise reduction processing.
While effective at capturing most of the noise, it may not accurately determine the direction of the noise, potentially missing some sounds.

Feedback noise cancellation:

In this method, the microphone is placed inside the headphones, closer to the sound heard in the ear.
The microphone picks up the noise, and the headphones send a signal to the DSP for noise reduction processing.
The microphone continues to detect residual noise and constantly compares it to the noise reduction algorithm to achieve better results.

Hybrid noise cancellation:

This approach combines both feed-forward and rear feedback techniques, utilizing two microphones.
One microphone faces outward to capture external noise, while the other is positioned inside the headphones.
The noise collected by both microphones is processed by the DSP, resulting in more accurate and efficient noise cancellation.

While active noise cancellation is incredibly effective at reducing low-frequency noise, such as car engine sounds or airplane cabin noise, it may have limited impact on high-frequency sounds like human voices. To address this, many headphones incorporate "passive noise reduction" techniques to physically minimize ambient noise, especially in environments where voices are prevalent.

Noise-canceling headphones not only create a tranquil listening environment but also offer additional benefits. They provide an immersive audio experience while protecting your hearing, making them ideal for noisy environments where headphones are frequently worn.

Here are a few exceptional noise-canceling headphones we recommend: